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Neuromuscular Physiology
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
From a gross anatomical aspect, muscle fibers are arranged into two basic structural patterns: fusiform or pennate (also spelled pinnate). The fusiform arrangement makes up most human muscle, with the fibers largely arranged in parallel arrays along the muscle’s longitudinal axis with tendons at the proximal and distal ends. In many of the larger muscles the fibers (and the fascicles) are inserted obliquely into the tendon, and this arrangement resembles a feather (i.e., pennation). Pennate muscle fibers are typically shorter than those of a fusiform muscle and insert on their tendons in several different manners forming uni-, bi-, and multipennate muscles. Fusiform fibers can largely run parallel, converge or form a circular arrangement; the various arrangements of human fusiform and pennate muscle fibers are shown in Figure 1.1.
Lower Limb Muscles
Published in Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Handbook of Muscle Variations and Anomalies in Humans, 2022
Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Malynda Williams
There are very few descriptions of muscles that researchers believe correspond to tenuissimus in humans. Green (1931) describes one case in the right thigh of a cadaver. Tenuissimus presented as a fusiform muscle that arose via an expanded aponeurosis and subsequent tendon from the fascia covering the deep surface of gluteus maximus. The muscle belly descended the thigh and inserted onto biceps femoris at the junction of the short head and the long head, with a slightly more extensive attachment to the long head. Green (1931) mentions a similar case that was described by Wood (1867b) as a third head of biceps femoris. It arose via a rounded tendon from the fascia on the deep surface of gluteus maximus and inserted onto the long head of biceps femoris near its junction with the short head.
Achilles disorders
Published in Maneesh Bhatia, Essentials of Foot and Ankle Surgery, 2021
Maneesh Bhatia, Nicholas Eastley, Kartik Hariharan
Gastrocnemius is a fusiform muscle made principally of fast twitch type II fibres. The muscle acts across three joints, primarily facilitating ankle plantarflexion (with soleus) but also assisting in knee flexion and subtalar inversion. By transmitting forces from the triceps surae, the AT is key in each of the three gait rockers. During the first rocker, eccentric gastrocnemius contraction follows heel strike ensuring a controlled progression into the stance phase. Next, controlled soleus contraction facilitates the forward transfer of body weight over the ankle (second rocker), before concentric gastrocnemius contraction and eccentric Tibialis Anterior contraction facilitates toe off during the third rocker (when AT forces may reach 12.5 times a patient's body weight).
Assessing thigh muscle balance of male athletes with special emphasis on eccentric hamstring strength
Published in The Physician and Sportsmedicine, 2020
Tobias Alt, Axel J. Knicker, Heiko K. Strüder
The relation between DCR and eccentric hamstring moment and work was moderate (25% ≤ R2 ≤ 46%) (Figure 3) because hamstring and quadriceps strength were weakly associated to each other (17% ≤ R2 ≤ 25%). These numbers confirmed current research emphasizing that strength capacities of the knee flexor and extensor muscles are fairly independent of each other [38]. As mentioned above, sports-related performance does not only rely on eccentric hamstring peak moments but also on contractional work. In contrast to DCRe moment whose coefficients of determination remained nearly unchanged when comparing PMHecc and CWHecc at 150°/s, those of DCR were 21% lower for CWHecc compared to PMHecc (Figure 3(b,d)). These results underline the limited applicability of DCR to movements across the full range of motion especially at high isokinetic movement speed [9]. The relationship between DCR and eccentric hamstring moments was 17% stronger at 150°/s compared to 30°/s, whereas those of DCRe moments were similar (Figure 3(a,b)). This might be explained by a lower variance of data obtained from the quadriceps working at a high angular velocity [18,20]. Additionally, the hamstrings are a fusiform muscle group which is specialized for fast contractions [39].
Extra-articular hip impingement: clinical presentation, radiographic findings and surgical treatment outcomes
Published in The Physician and Sportsmedicine, 2019
The iliopsoas tendon has been considered to be the conjoint tendon of the psoas major and iliacus muscles [7]. The psoas major is a long, fusiform muscle originating from the lumbar transverse processes, traversing distally over the anterior aspect of the hip joint, terminating in a tendon attaching to the lesser trochanter [7]. The iliacus muscle originates from the iliac fossa and iliac crest, traversing distally to join the lateral margin of the psoas major tendon [7]. The iliopsoas tendon lies immediately anterior to the hip joint, overlying the femoral head, bordered medially by the iliopectineal ridge and laterally by the anterior iliac spine [7].
Development of a finite-element muscle model accounting for transverse loading
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
M. Maamir, L. Chèze, B. Fréchède
A 3D continuum hyperelastic transverse isotropic law, commonly used in the literature (Blemker et al. 2005; Röhrle et al. 2017), was implemented in the FE code LS-DYNA® (LS-DYNA 2018) as a user defined material routine, where the stress combines the contribution of a Mooney–Rivlin function and of a unidirectional Hill-type model. A calibration of the axial active-passive force-length behaviour was first performed (case A) by modelling the simplified geometry and material properties (Figure 1(A1)) of a rabbit Tibialis Anterior (TA) muscle and by simulating the experimental behaviour measured during a sequence of passive lengthening, isometric and eccentric active contractions reported by Davis et al. (2003) (Figure 1(A2, A3)). A cylindrical fusiform muscle (Figure 1(B)) with generic human neck muscle material properties was then modelled to reproduce the experimental protocol from (Siebert et al. 2014) where an isometric contraction was applied under transversal weight-bearing loading conditions (Figure 1(B)/case B). In this case the activation level was controlled to try and reproduce the phenomenological transverse/longitudinal force coupling that had been observed by Siebert et al. and to investigate its quantitative effects on a representative neck muscle. The possible mechanistic influence of the presence of an aponeurosis on this coupling was also investigated by extruding and attaching tension-only shell elements to the outside mesh of the model. Young’s modulus of the aponeurosis where chosen ranging from 0.1 MPa to 1 GPa (a wider range of conjunctive tissue stiffnesses than reported in the literature), to assess the model’s sensistivity to this parameter. The axial force generated by the muscle, the lifting height of the weight (measured as its relative displacement induced during the contraction-only phase) were output and compared to the experimental results (Table 1).